Overhaul Auto-Type Action Handling

* Close #2603 - Add support for modifier syntax (+, ^, and %)
* Fix #2633 - Allow reference syntax {REF:...} in Auto-Type sequences
* Close #5334  - Tell the user which part of the Auto-Type sequence is invalid for easy correction
* Fix #2401 - Select the right window on macOS prior to starting Auto-Type

* Allow for nested placeholders

src/gui/MainWindow.cpp

@@ -1613,6 +1613,13 @@ void MainWindow::toggleWindow()
     }
 }
 
+void MainWindow::closeModalWindow()
+{
+    if (qApp->modalWindow()) {
+        qApp->modalWindow()->close();
+    }
+}
+
 void MainWindow::lockDatabasesAfterInactivity()
 {
     m_ui->tabWidget->lockDatabases();